The invention relates to a screw rotor machine for a compressible working medium with a screw cam rotor and a screw thread rotor enclosing the screw cam rotor which rotors are rotatably journalled in a housing for rotation around mutually sideways displaced fixed rotation axes and thereby between their screw cam means and screw thread means form chambers for the working medium which chambers during rotation of the rotors move from end to end of the rotors while changing their volumes.
In such screw rotor machines of which suggestions are shown e.g. in Swedish Pat. No. 85.331 and U.S. Pat. No. 1.892.217 practical operation at high numbers of revolution and pressure suitable for now actual compressor or motor applications has hitherto not been realized. According to prior suggestions the bearings of the screw thread rotor are exposed to the entire axial load which follows from the pressure of the working medium against the end of the screw thread rotor. The design suggestions are, therefore, only suitable for low pressures and numbers of revolution which result in a low compressor capacity or motor power.